Jig for manufacturing of firearm lower receiver

ABSTRACT

An improved jig for manufacturing a firearm lower receiver is comprised of a power tool mount; an adapter; a guide plate with plate screws; a rear support with mounting screws; a front support; and at least one of a carriages with at least one locating pin. A guide plate is disposed below the top surface of a lower receiver in conjunction with an adapter. The jig is a universal fitment and includes a bearing to support a rotary tool and at least one guiding feature can be used to facilitate in the guidance of the rotary tool without placing the rotary tool in direct contact with any of the guidance features. A removable locating pin is situated a long the front and rear takedown pin holes of a firearm receiver that is not threaded and is provided with at least one of a pull, string or other handle.

RELATED APPLICATIONS

This application is a continuation of co-pending U.S. application Ser.No. 15/979,322 filed May 14, 2018, entitled IMPROVED JIG FORMANUFACTURING OF FIREARM LOWER RECEIVER, which application is acontinuation of U.S. application Ser. No. 15/726,351, filed Oct. 5,2017, entitled IMPROVED JIG FOR MANUFACTURING OF FIREARM LOWER RECEIVER,which application claims the benefit of U.S. Provisional ApplicationSer. No. 62/404,710, filed Oct. 5, 2016, entitled IMPROVED JIG FORMANUFACTURING OF FIREARM LOWER RECEIVER, the entire disclosures of eachof which applications is hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to systems and methods for manufacturing an 80%(partially unfinished) firearm receiver, with a high rate of successwith improved quality, by an unskilled user.

BACKGROUND OF THE INVENTION

A market exists for incompletely/partially manufactured firearm lowerreceivers. A firearm lower receiver is unregulated until a minimum levelof manufacturing is completed. This level is typically known as “80%”.Firearm lower receivers completed to this level are typically referredto as “80%” lower receivers. These firearms must then be completed bythe end user to be operable. In a typical configuration the lowerreceiver is cast and/or forged and is partially machined, with certainaspects of the inner slot (in which the trigger mechanism resides)remaining uncut. The finishing task cuts this remaining slot withappropriate dimensions and accuracy.

The completion of these lower receivers can be time consuming andquality results may be difficult to achieve with prior art. Inaccordance with the prior art, the technique for finishing the receivercan place a rotary power tool in a position that is effectively too faraway from the lower receiver. As such this prior art technique canproduce poor results and broken tooling. Additionally, the prior arttechnique can involve placement of a rotating tool in direct contactwith guiding areas of a jig, which can result in premature wear.

It would be desirable to provide a jig assembly that effectively reducesthe unsupported distance between the rotary power tool and the 80% lowerreceiver and that avoids direct contact between the rotating tool andits guiding features.

SUMMARY OF THE INVENTION

This invention overcomes the disadvantages of the prior art by providinga device that reduces the distance between the lower receiver and therotary power tool and by using additional features to guide the rotarytool instead of placing it in direct contact with any of the pluralityof guiding features. An improved jig for manufacturing a firearm lowerreceiver is comprised of a power tool mount; an adapter; a guide platewith plate screws; a rear support with mounting screws; a front support;and at least one carriage with at least one locating pin. A guide plateis disposed around and below the top surface of a lower receiver and ismounted to the carriage(s) in conjunction with a rotary power tooladapter. The jig is a universal fitment. The jig includes a bearing tosupport a rotary tool and is constructed and arranged to provide for useof at least one guiding feature to facilitate in the guidance of therotary tool without placing the rotary tool in direct contact with anyof a plurality of guidance features for firearm lower receivermanufacturing. A removable locating pin is situated in a location alongthe front and rear takedown pin holes of a firearm receiver that is notthreaded and is provided with at least one of a pull, a string or otherhandle for firearm lower receiver manufacturing.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention description below refers to the accompanying drawings, ofwhich:

FIG. 1 is an exploded right side view of an improved jig, according toan illustrative embodiment;

FIG. 2 is a right side view of the improved jig, according to theillustrative embodiment;

FIG. 3 is an exploded rear view of the improved jig, according to theillustrative embodiment;

FIG. 4 is a rear view of the improved jig, according to the illustrativeembodiment;

FIG. 5 is an exploded left side view of the improved jig, according tothe illustrative embodiment;

FIG. 6 is a left side view of the improved jig, according to theillustrative embodiment;

FIG. 7 is an exploded front view of the improved jig, according to theillustrative embodiment;

FIG. 8 is a front view of the improved jig, according to theillustrative embodiment;

FIG. 9 is a exploded perspective view of the improved jig, according tothe illustrative embodiment;

FIG. 10 is a perspective view of the improved jig, according to theillustrative embodiment;

FIG. 11 is a top view of the improved jig, according to the illustrativeembodiment;

FIG. 12 is a top view of the improved jig, according to the illustrativeembodiment;

FIG. 13 depicts a method of jig assembly according to one or moreaspects of the disclosure;

FIG. 14 depicts a method of drilling with a jig assembly according toone or more aspects of the disclosure;

FIG. 15 depicts a method of milling with a jig assembly according to oneor more aspects of the disclosure;

FIG. 16 depicts a method of milling with a jig assembly according to oneor more aspects of the disclosure;

FIG. 17 depicts a method of milling with a jig assembly according to oneor more aspects of the disclosure;

FIG. 18 depicts a method of drilling with a jig assembly according toone or more aspects of the disclosure;

FIG. 19 depicts a method of lower receiver removal using a jig assemblyaccording to one or more aspects of the disclosure;

FIG. 20 depicts various components of a jig assembly with reference toFIGS. 13-19 and 21-27;

FIGS. 21A-P depict various stages of the method of FIG. 13;

FIGS. 22A-I depict various stages of the method of FIG. 14;

FIGS. 23A-K depict various stages of the method of FIG. 15;

FIGS. 24A-K depict various stages of the method of FIG. 16;

FIGS. 25A-E depict various stages of the method of FIG. 17;

FIGS. 26A-G depict various stages of the method of FIG. 18; and

FIGS. 27A-E depict various stages of the method of FIG. 19.

DETAILED DESCRIPTION

The primary function of a jig is to provide repeatability, accuracy, andinterchangeability in the manufacturing of products. In FIG. 1, animproved jig 100 is assembled by placing left carriage 302 (see FIG. 3,not shown in FIG. 1) on the left side of a lower receiver 116 and byplacing right carriage 114, on the right side of the lower receiver 116.The lower receiver in this example is a form of popular AR-stylereceiver (for example the semi-automatic version of the AR-15, M-16, M-4carbine, and variants thereof). The lower receiver is the portion of thefirearm that includes a shoulder stock, pistol grip, trigger mechanismand magazine well. The upper receiver includes the barrel, chamber andbolt assembly. The lower receiver is attached to the upper receiver bytwo takedown pins. The firearm is available in fully automatic andsemi-automatic versions. Note that the jig is adapted to finish thereceiver with holes and cuts appropriate to the semi-automatic version.However, the jig can be adapted for the use by licensed manufacturers tofinish other versions (e.g. fully automatic) of the firearm. The jig 100is an assembly that is comprised of a rotary power tool mount 103, anadapter 122, a guide plate 108 with plate screws 106, 120, a threadedrear support 110 with mounting screws 112, a front support 118, and atleast one carriage 114 with at least one locating pin 306. As describedbelow, the plate screws 106 are machine screws with an appropriatediameter, thread size and length, and the screw 120 can also be amachine screw (for example, a #8-32 flat head machine screw), sheetmetal screw, or another form of self-tapping screw. The receiving holeof the front support 118 is drilled and/or tapped to accommodate thescrew 120. The illustrative jig defines a universal fitment. A removablelocating pin 306 (See FIG. 3) is readily inserted through all threeparts 302, 116 and 114 to hold them in alignment relative to each other.This renders assembly highly straightforward for use by even aninexperienced user. In an embodiment, the jig assembly can be providedas a kit with appropriate instructions (printed, on electronic mediaand/or available via the Internet). See for example, the instructions inattached Appendix A, which describe setup and use of the jig assembly.The kit can include a rotary power tool having and appropriate size,shape, torque and power supply.

As described herein, the lower receiver 116 includes a buffer mount 117for receiving a buffer assembly within the shoulder stock at one end,and the front surface of the magazine well 119 at the other. As definedherein, the buffer mount 117 is at the “rear” end of the lower receiver,while the magazine well 119 is at the “front” end of the lower receiver.As presented in FIG. 1, the rear end of the lower receiver 116 is on theleft side and the front end of the lower receiver 116 is on the rightside and the visible face of the lower receiver is the “right” side. Theright carriage 114 is resting on the right side of the lower receiver116. Thus, the relative orientation of the jig assembly 100 (i.e. left,right, front, rear, top and bottom) is described with respect to thecorresponding, confronting sides of the lower receiver 116.

Note that the carriage plate 114 is provided with three drill guideholes, 132, 134, 136, along its side for the location of and drilling ofappropriate diameter pin holes into the lower receiver 116. These guideholes are used to guide and align a drill bit to bore desired holes intothe lower receiver side. By way of non-limiting example drill guide hole132 is a guide hole for a hammer pivot/pin hole, for the subsequentmounting of an assembly that retains the hammer mechanism within thelower receiver. Drill guide hole 134 is a guide hole for a triggerpivot/pin hole, for the later mounting of a trigger pivot/pin to retainthe trigger mechanism. Drill guide hole 136 is a guide hole for aselector/safety pivot hole, for the subsequent mounting of aselector/safety lever. These carriage guide holes provide for theaccurate and precise placement of the pin holes and are constructed sothat an unskilled user can properly place the pivot/pin holes forcompletion of the assembly of a functioning lower receiver. Holes can beprovided on each of opposing carriage plates to drill each side of thereceiver in an embodiment. In alternate embodiments holes are providedon one side and the drill passes through both sides of the receiver. Thethickness of the carriage plate(s) and close tolerance of the hole tothe drill shaft is sufficient to ensure minimal skew or wobble as thedrill passes into the receiver side.

The rotary power tool mount 103 is adapted to receive an appropriatelysized and shaped rotary power tool 102, as described further below. Therotary power tool retains an appropriate rotary tool 104 in accordancewith various embodiments. The term “rotary tool” shall be taken broadlyherein to mean any one of a variety of rotating cutting elements thatcan be mounted removably (or permanently) within a chuck or arbor of therotary power tool 102. For example a two-flute or four-flute end mill ofappropriate diameter (for example, a ¼ inch diameter, or anotherappropriate diameter between (e.g.) ⅛ inch and ½ inch) can be mountedwithin the rotary power tool. The mill can include a cutting end and ashaft that is free of cutting surfaces. The shaft is adapted to confrontthe jig so as to avoid cutting its sides while the cutting end isadapted to reside within the receiver so as to cut the appropriateslot(s) in conjunction with the jig's outline(s). The rotary tool 104can be constructed from a variety of high-strength materials, such ashigh-speed steel, tungsten carbide, etc.

As shown, the rear support 110 is threaded into lower receiver 116 viathe receiver's rear buffer mount (a large round hole at the rear of thereceiver in which a buffer assembly normally resides when assembled intoa firearm). Front support 118 is placed between two mounting ears on thelower receiver 116 before an easily removable locating pin 704 insertedthrough the mounting ears of the lower receiver 116 and through the holein the front support 118. Illustratively, the front support 118 resideswhere the front pivot/takedown pin between the upper and lower receiveron a complete firearm normally resides. The pivot hole in thisarrangement has been drilled by the supplier of the 80% receiver, andis, thus available for use in mounting the front support via pin 306. Aswith other receiver holes and structures relied upon to engage the jigassembly, they are reliably located by the manufacturer usingsophisticated tooling so that the jig accurately and repeatable mountedto the lower receiver 116, and the corresponding cutting performed bythe user is equally reliable and accurate.

After mounting the front support 118, a guide plate 108 is then placedatop the assembly by aligning the holes in the guide plate 108 with thethreaded holes in the front support 118, the threaded holes in the rearsupport 110, and the threaded holes in both the left and right carriages302 and 114 respectively. The guide plate 108 has a thickness TC1 ofbetween ⅜ and up to ½ inch and a length LC1 of approximately 8 inches(±0.5 inches). The adapter plate 122 has a thickness TC2 ofapproximately ½ inch and a length LC2 of approximately 4 inches (±0.5inches). In other embodiments, these thicknesses and widths can varygreater or lesser, depending on the materials used. Once aligned,carriage-to-guide plate screws 106 are inserted through the guide plate108 and tightened to connect the carriages 114 and 302 to the guideplate 108. The rear support-to-guide plate screws are inserted throughthe holes in the guide plate 108 and tightened into the rear support110. The front support-to-guide plate screws 120 are inserted throughthe guide plate 108 and tightened into the front support 118. Thesescrews 120 can be sheet-metal screws or flat head screws (for example, a#8-32 flat head screw) and the hole(s) in the front support 118 can besized to receive such screws. The carriage screw 304 is threaded to acorresponding female thread in the left carriage 302 and continuedthrough a threaded hole in the right carriage 114. Illustratively, boththe left carriage 302 and right carriages 114 are threaded so if theassembly is placed into the jaws of an external vice or other clamp, itwill tend to resist deformation that could damage the lower receiver 116sandwiched therebetween. The screw 304 can have a recessed drive head(e.g. hex, star, etc.) so that it avoids interference with a clampingjaw (if any). The above thus defines the full set of components of thejig assembly, which are connected either directly or indirectly to thelower receiver 116.

The illustrative jig assembly is depicted as retaining a rotary powertool 102 in the power tool mount 103, but it is contemplated that thepower tool can be a non-rotary tool. The jig provides for the use of atleast one of the various guiding features (for example, left carriage302) to be utilized to aid in the guidance of a power tool 102 withoutplacing the tool in direct contact with any guiding feature.

Note that a wide variety of rotary power tools can be employed inassociation with an embodiment of the jig assembly—for example a smallrouter, drill, hand piece of a flexible-shaft unit or Dremel®-styletool. The rotary tool can be cordless or powered by (e.g.) wall currentvia a power cable.

FIG. 2 depicts the jig 100 holding the rotary power tool 102 inengagement with the lower receiver 116 so that finishing work can beperformed on the lower receiver. The receiver 116 is situated betweenthe carriages 114 and 302 so that it remains in place during thefinishing operation. There is a narrow gap between the carriages and thewalls of the lower receiver 116. The gap prevents contact between thesurfaces of the carriages with the surface of the lower receiver andthereby prevents possible scratching of the surface coating of the lowerreceiver. In an alternate embodiment, the carriages can have an externalflexible coating (for example, a polymer) and make contact with thesurface of the lower receiver or a removable foam pad can be providedduring assembly to avoid inadvertent contact between the carriage plateand the receiver during assembly of the jig. The various plates of thejig assembly can be constructed from a variety of materials, orcombination of materials—for example aluminum alloy, steel, polymer(e.g. Delrin® (from DuPont), polycarbonate, acrylic, etc.). Thethickness of each plate 108, 122 is also highly variable, and depends inpart upon the choice of material(s). By way of non-limiting example, thethickness of the jig assembly plate(s) can be between ⅛ and ½ inch, orgreater, for sufficient strength and rigidity. For example, the carriageplates 114 and 302 should define a sufficient thickness to receive thescrews 106 within threaded holes formed in the top edge of each plate.Likewise, the guide plate 108 should be sufficiently thick to allow therotary tool 104 to resist wobble. The various plates can be constructedfrom sheet stock and milled to shape using, e.g. CNC manufacturingtechniques. Other methods of constructing the plates can be employed inalternate embodiments—for example stamping or casting with finishmilling, 3D printing, molding, etc.

The following is a description further views and representations of theassembled jig assembly 100 and corresponding rotary power tool (102)arrangement.

With reference to FIG. 3, a rear-oriented exploded view of the jigassembly 100 is shown, with the rear support 110 with mounting screws112 visible within the buffer mount 117 within the lower receiver 116.In an embodiment the carriage plates 114 and/or 302 can define athickness TC3 of approximately ½ inch (+⅛ inch). This dimension ishighly variable in alternate embodiments an, in part, facilitates theformation or female-threaded holes for receiving screws 106. Note that,while two carriage plates are employed in the depicted embodiment, atleast one carriage plate can be used in alternate arrangements. Such asingle plate can include appropriate brackets or other structures tomaintain it in confronting, accurate engagement with the lower receiverside.

With reference to FIG. 4 a rear view of the assembled jig 100 is shownin operation on the lower receiver 116. The carriage plates 114, 302 aresituated on their respective sides of the lower receiver 116 and areheld in place by removable pins 306 and 704. Each of the pins isremovably locked in place by a detent 307 located at one end and a ring309 at the other. Opening 402 in the tool mount 103 serves to provideair circulation within the area of the machining, a portal for theegress of machining debris and a visible window to allow a view of themachining in process.

FIG. 5 is an exploded left side view of the jig 100 in an assembledstate, with a rotary power tool 102, a rotary power tool adapter 122, arotary tool 104, a guide plate 108, a rear support 110, a left carriage302, a lower receiver 116, a front support 118 and related mechanisms.The buffer mount 117 protrudes through guide plate 108. Plates 108 and122 support the rotary power tool above the lower receiver 116 such thatthe rotary power tool is not resting upon the lower receiver.

As described above, the left carriage plate 302 is also provided withthree drill guide holes, 632, 634, 636, for the location of and drillingof pivot/pin holes into the lower receiver 116 that are aligned with theright carriage holes 132, 134 and 136, respectively and define the samedimensions. In embodiments in which a pin/pivot defines differentdiameters on each side, or is eccentric the diameter or placement of theleft carriage hole can vary relative to that of the right carriage hole.

FIG. 6 is a collapsed view of FIG. 5 illustrating; a rotary power tool102, a rotary power tool adapter 122, a guide plate 108, a left carriage302, a lower receiver 116 and a front support 118.

FIG. 7 is an exploded front view of the illustrative jig 100. Pin 704 ispositioned to be inserted through takedown pin mounts 702, such that thepin 704 passes through the front support 118 and the pin mounts 702,thereby locking the front support 118 to the lower receiver 116. The pinmounts are through holes in the lower receiver 116. In anotherembodiment, pins 306 and 704 can define a bolt with a removable nut forlocking the bolt in place.

FIG. 8 is a collapsed view of the jig 100 with particular attentioncalled to the placement of the locating pins 306, 704 in the pin mounts702 and are held in place by detents 307. The locating pin 306 isremovable and is situated in a location along the front and reartakedown pin holes of a firearm receiver that is not threaded and isprovided with at least one of a pull, a string or other handle forfirearm lower receiver manufacturing.

FIG. 9 is a bottom view of the jig 100. The bottom surface of adapter122 includes a plurality of wells 901 of various sizes, angles andshapes disposed across the surface of the adapter 122. A rotary powertool support bearing 902 is inserted into the rotary power tool adapter122 (for example—using a press or other biasing device) in a circularwell 901 located near the center point of the adapter 122. Bearing 902allows movement of a rotary power tool which further supports the rotarytool, thereby increasing rigidity, user control, and thus, quality. Therotary tool 104 is then inserted into the rotary tool support bearing902 and the rotary power tool adapter 122 is connected to the rotarypower tool 102 by inserting adapter screws 906 into their respectivewells 901 in the adapter 122 and tightened into adapter 103. The guidepins 908 are connected to the adapter 122 by inserting an adapter screw904 through the guide pins 908 and tightened into the adapter plate. Theabove thus defines the components of the tooling assembly.

In use, the rotary power tool 102 and mount 103 and adapter 122 areplaced on top of the guide plate 108 and assembled, as described above,to form the jig. The guide pins 908 are placed into the guide cavities1202 located within the guide plate 108. The rotary tool 104 protrudesby a predetermined length from adapter 122 so as to interface with thelower receiver 116 situated below guide plate 108. The geometry of thewalls of the lower receiver are generally vertical, with the walls ofeach side parallel to each other up and down and front to back. Thisgeometry provides an opportunity for the unskilled user to complete themachining of the receiver and the performance of the machining tools isoptimized by the stability of the jig. The rotary power tool 102,adapter 122, rotary tool 104, guide pins 908, and connecting screws 904and 906, are then guided within the guide cavities 1202. The location ofthe guide pins 908 and guide cavities 1202 are placed as to locate therotary tool 104 in a predetermined location within the lower receiver116 to achieve the desired results without placing the rotary tool 104in direct contact with any components other than the lower receiver 116,thus reducing premature wear. Window 920 is a cutout slot at the rear ofadapter 122 and provides visual and physical access to the lowerreceiver during machining operations, as well as preventing contact withthe buffer mount 117.

FIG. 10 is a collapsed view of FIG. 9 showing the protrusion of therotary tool 104. Window 920 is aligned to the rear of the jig.

FIG. 11 is a top view of the jig 100 without the rotary power tool.Indices 1102, 1104, 1106 are located along a surface of guide plate 108and are depth references for the end milling process. Each of theindices is a cavity, as shown in FIG. 1. Indices 1102, 1104 and 1106relate to three different lengths for guide pins and the guide cavitiesare stepped at three different heights so that as the pins get longer,the guide describes a smaller area. The alignment of the view of FIG. 11is that the top of the view is the front of the jig and the bottom ofthe view corresponds to the rear of the jig. Buffer mount 117 isdepicted as protruding through guide plate 108.

FIG. 12 is the same view as FIG. 11 with the rotary power tool adapterviewed as semi-transparent, allowing a better view of a rotary tool 104,a guide plate 108 incorporating guide cavities 1202; a lower receiver116 and guide pins 908 residing within their respective wells 901. Theshape of the guide cavities 1202 corresponds to the shape of theinternal walls of the lower receiver 116 such that when the rotary tool104 is inserted into the lower receiver 116, the operator maneuvers theguide pins 908 against the walls of the guide cavities 1202 and canaccurately machine the internal surfaces of the lower receiver 116.

In operation, the user places carriages 114 and 302 in a vise or otherclamping device to hold steady. The protrusion depth of the rotary tool104 is set using indices 1102, 1104, 1106. In practice, this is done byplacing rotary tool 104 within the indices and aligning to theappropriate hash mark for the required milling step and moving therotary power tool adapter 122 into contact with the edge of guide plate108 therefore setting the protrusion depth to the appropriate hash markrelative to the bottom surface of adapter 122

The assembled rotary power tool 102, mount 103, rotary tool 104, adapter122 and guide pins 908 are engaged with the guide plate 108 and guidecavities 1202. When the assemblies are placed atop each other with guidepins 908 within guide cavities 1202 the rotary power tool is switched onand rotary tool 104 begins to rotate at a high rate of angular velocity.The user grasps either the rotary power tool 102, mount 103 or adapter122 and slide the adapter 122 along the guide plate 108. The protrudingguide pins 908 contact the walls of the guide 1202 preventing rotarytool 104 from milling into the incorrect locations. This task iscontinued until guide pins 908 have been translated through the entireguide cavities 1202 removing all the material that rotary tool 104 hascontacted within the lower receiver 116. The rotary power tool 102 isthen switched off and the rotary tool 104 is allowed to come to rest.The assembled rotary power tool 102, mount 103, rotary tool 104, adapter122 and guide pins 908 are then lifted off of the guide plate 108. Therotary tool 104 is then placed back into indices 1102, 1104, 1106 toadjust the protrusion depth to the next hash mark of the respectiveindex. When the depth is properly set, the assembled rotary power tool102, mount 103, rotary tool 104, adapter 122 and guide pins 908 arere-engaged with guide plate 108 and guide cavities 1202. The sameprocedure is followed to remove this material with rotary tool 104 fromlower receiver 116. This procedure is similarly followed until allmaterial is removed from lower receiver 116. Chips can be removedperiodically during each cutting task using a vacuum or by rotating thereceiver and jig assembly upside down.

In order to guide rotary 104 properly in lower receiver 116 to allow forproper function, guide cavities 1202 have additional cavities containedwithin them. For example, the entire guide cavity 1202 is milled to adepth greater than 1/16 inch but less than ⅛ inch. A further reducedarea within guide cavity 1202 is milled to a depth greater than ⅛ butless than 3/16 inch. Yet another area within the reduced area is milledto a depth greater than 3/16 inch. This allows for two reduced areacavities within the larger guide cavity 1202. Guide pins 908 can beinterchanged with varying lengths to allow for the assembled rotarypower tool 102, mount 103, rotary tool 104, adapter 122 and guide pin908 unit to be engaged in either the full guide cavities 1202 or withinthe reduced area cavities within guide cavities 1202. If a guide pin 908has a length greater than zero but less than ⅛ of an inch, it wouldguide within the entire guide cavities 1202. If a guide pin 908 has alength greater than ⅛ but less than 3/16 of an inch, similarly it wouldguide within the reduced area within the guide cavities 1202. Finally,if a guide pin 908 has a length greater than 3/16 of an inch it would beguided within the cavity within the reduced area cavity which is withinthe guide cavities 1202. With this arrangement, the assembled rotarypower tool 102, mount 103, rotary tool 104, adapter 122 and guide pins908 can guide the rotary tool 104 to various shapes within the lowerreceiver by interchanging the guide pins 908 length.

FIGS. 13-19 depict various methods with reference to FIGS. 20-27.

FIG. 13 depicts a method 1300 of jig assembly according to one or moreaspects of the disclosure.

At block 1302, and with reference to FIGS. 21A-B, thread the bufferadapter 7 into lower receiver. The buffer adapter 7 should sit justbelow surface of the lower receiver with threaded holes sittinghorizontal. If the buffer adapter 7 is difficult to thread, #8-32 screws15 can be installed for leverage.

At block 1304, and with reference to FIGS. 21C-D, orient side plates 3,4 on each side of the lower receiver, taking note of right and left asit would be oriented in a shooting position. Insert long quick releasepin 10 through right side plate, through receiver rear takedown, and outleft side.

At block 1306, and with reference to FIGS. 21E-F, place the drill guide2 between side plates as shown and align screw holes. It should alignonly one way. Pinch side plates against drill guide and tighten four#8-32 screws 15.

At block 1308, and with reference to FIGS. 21G-H, use 3/16″ Allen wrenchto thread ¼-20×2″ screw 13 through left side plate 4 and into rightplate 3 using care not to cross-thread.

At block 1310, and with reference to FIGS. 21I-J, align the fronttakedown adapter 8 between front takedown holes. Push the short quickrelease pin 11 through receiver and adapter as shown.

At block 1312, and with reference to FIGS. 21K-L, place the guide plate1 atop side plates 3, 4 as shown. Align screw holes on guide plate 1with buffer adapter 7 screw holes. Thread two #8-32 screws 15 and leaveloose.

At block 1314, and with reference to FIGS. 21M-N, align front takedownadapter 8 (not shown) with holes in guide plate 1. Insert and tightentwo #8-32 screws 15, tightening each screw a little at time. Now,tighten two #8-32 screws 15 from blocks 1302-1312. The buffer adapter 7will self-center in buffer mount. Guide plate 1 may move as these aretightened. Allow guide plate to move freely during tightening.

At block 1316, and with reference to FIGS. 21O-P, loosely thread six¼-20×½″ screws 14 through guide plate 1 and into side plates 3, 4.Tighten screws using 3/16″ Allen wrench. The jig assembly is nowcomplete.

FIG. 14 depicts a method 1400 of drilling with a jig assembly accordingto one or more aspects of the disclosure.

At block 1402, and with reference to FIG. 22A, slide ⅜″ drill stop ontoshank of ⅜″ drill bit. Insert drill bit to full depth of depth gauge #21104. Place the drill stop against the edge of the guide plate 1. Securedrill stop onto drill bit.

At block 1404, and with reference to FIGS. 22B-C, spray WD-40 into hole#2 of the drill guide 2. Insert ⅜″ drill bit into hole. Do not startdrill until bit is fully inserted. Start drill and apply firm pressure.Periodically, lift drill to assist in chip removal. Reapply WD-40 asnecessary. Stop drilling just before the drill stop touches the drillguide 2.

At block 1406, and with reference to FIGS. 22D-E, prior to drilling,ensure that jig assembly is level. Spray WD-40 into hole #3 of drillguide 2. Insert 5/16″ drill bit into hole. Do not start drill until bitis fully inserted. Start drill and apply firm pressure. Periodically,lift drill to assist in chip removal. Reapply WD-40 as necessary. Stopdrilling when the drill bit exits the bottom of the fire control pocket.Take care not to drill into the trigger guard. In this example, keep thedrill bit perpendicular to the lower receiver. Drilling at a large anglecan result in an oblong trigger slot.

At block 1408, and with reference to FIGS. 22F-G, remove four #8-32screws 15 and remove the drill guide 2. It may be necessary to loosenthe vise and/or use a screwdriver to gently pry the drill guide frombetween the side plates. Insert the screw driver shank into hole #2 andgently pry upward.

At block 1410, and with reference to FIGS. 22H-I, remove long quickrelease pin 10 from rear takedown hole.

FIG. 15 depicts a method 1500 of milling with a jig assembly accordingto one or more aspects of the disclosure.

Initially, prepare your router for milling by installing the universalrouter adapter 5. If using a variable speed router, start router onslowest speed and gradually increase speed until optimal milling resultsare achieved. Generally speaking, this will equate to speed “2” to speed“4” on most variable models with “1” to “10” speed adjustments. Do notinsert or remove router while it is spinning. Move router smoothly in aclockwise manner, do not mill in straight lines for extended periods.Avoid abruptly pulling the end mill or exerting excessive force to movethe end mill. Apply WD-40 liberally while milling to reduce excess heat.Remove chips whenever necessary.

At block 1502, and with reference to FIGS. 23A-B, install #1 (short)guide pins 9 on router adapter 5 using the two smallest socket capscrews and 7/64″ Allen wrench. Open end of pins should be facing up.Make sure pin seats are clear of debris prior to installing. Check thatguide pins are properly seated.

At block 1504, and with reference to FIG. 23C, set end mill depth to thefirst hash mark using depth gauge #1 1102. Set depth by holding base ofrouter adapter 5 against the edge of the guide plate 1. Be sure guidepins 9 are not between adapter and guide plate. Make sure router depthadjustment is locked when complete.

At block 1506, and with reference to FIG. 23D, orient lower receiverassembly so the buffer extension is closest to the user. Place routerassembly atop guide plate 1, with end mill entering the earlier drilled⅜″ hole. The notched side of the router adapter should be facing thebuffer extension as shown. The guide pins should be positioned insidethe guide cavities on both sides. Turn router on slowest speed andincrease to operating speed once ready to mill. Mill using consistentpressure and speed, moving in a clockwise manner.

At block 1508, and with reference to FIG. 23E, make the first pass ofmilling allowing the guide pins to follow the entire area of the guidecavities. When milling corners, gently twist the router side to side toassist to complete the entire corner radius.

At block 1510, and with reference to FIG. 23F, once the entire pass hasbeen milled to depth, set end mill depth to the second hash mark. Millsecond pass following the same method and process as shown in blocks1506-1508.

At block 1512, and with reference to FIGS. 23G-I, continue milling inthis manner, adjusting end mill depth by 1 hash mark until you reach thefinal hash mark of depth gauge #1. Do not attempt to mill more than 1hash mark, as it may result in poor quality, longer time and broken endmills.

At block 1514, and with reference to FIGS. 23J-K, complete the finalpass to full depth of depth gauge #1 and stop. Before continuing todepth gauge #2, the #2 (medium) guide pins 9 should be installed.

FIG. 16 depicts a method 1600 of milling with a jig assembly accordingto one or more aspects of the disclosure.

At block 1602, and with reference to FIGS. 24A-B, remove #1 (short)guide pins 9 and install #2 (medium) guide pins 9 on router adapter 5reusing the (2) screws and 7/64″ allen wrench. Make sure pin seats areclear of debris prior to installing. Check that guide pins are properlyseated.

At block 1604, and with reference to FIG. 24C, set end mill depth to thefirst hash mark using depth gauge #2. Set depth by holding base ofrouter adapter 5 against the edge of the guide plate 1. Be sure guidepins are not between adapter and guide plate. Make sure router depthadjustment is locked when complete.

At block 1606, and with reference to FIG. 24D, place router assemblyatop guide plate 1, with end mill entering the earlier drilled ⅜″ hole.The guide pins 9 should be positioned inside the #2 guide cavities onboth sides. Turn router on slowest speed and increase to operating speedonce ready to mill. Mill using consistent pressure and speed, moving ina clockwise manner.

At block 1608, and with reference to FIG. 24E, complete the first passallowing the guide pins 9 to follow the #2 guide cavities. When millingcorners, gently twist the router side to side to assist to complete theentire corner radius.

At block 1610, and with reference to FIG. 24F, once the entire pass hasbeen milled, set end mill depth to the second hash mark. Mill secondpass following the same method and process as outlined in blocks 1606and 1608.

At block 1612, and with reference to FIGS. 24G-I, continue milling inthe same manner, adjusting milling depth by 1 hash mark until you reachthe final hash mark of depth gauge #2. Do not attempt to mill more than1 hash mark, as it may result in poor quality, longer time and brokenend mills.

At block 1614, and with reference to FIGS. 24J-K, complete the finalpass to full depth of depth gauge #2. Start the end mill in the 5/16″pilot hole. Start the router at slowest speed setting and mill the holelarger before increasing the router speed. Once complete, stop. Beforecontinuing to depth gauge #3 1106, the #3 (long) guide pins 9 should beinstalled on the router adapter.

FIG. 17 depicts a method 1700 of milling with a jig assembly accordingto one or more aspects of the disclosure.

At block 1702, and with reference to FIGS. 25A-B, remove #2 (medium)guide pins 9 and install #3 (long) guide pins 9 on router adapter 5reusing the (2) screws and 7/64″ Allen wrench. Open end of pins shouldbe facing up. Make sure pin seats are clear of debris prior toinstalling. Check that guide pins are properly seated.

At block 1704, and with reference to FIG. 25C, set end mill depth usingdepth gauge #3. Set depth by holding base of router adapter 5 againstthe edge of the guide plate 1. Be sure guide pins are not betweenadapter and guide plate. Make sure router depth adjustment is lockedbefore when complete.

At block 1706, and with reference to FIGS. 25D-E, place router on guideplate 1, with end mill entering the earlier drilled 5/16″ hole. Theguide pins 9 should be positioned inside the #3 guide cavities on bothsides. Start the router at slowest speed setting and mill the holelarger before increasing the router speed. Gently mill in a clockwisemanner until the trigger slot is formed.

FIG. 18 depicts a method 1800 of drilling with a jig assembly accordingto one or more aspects of the disclosure.

At block 1802, clamp jig assembly in the vise by the guide plate 1 soright side plate is facing up and ensure that the assembly is level. Usea rag or cardboard between the vise and guide plate to prevent damage tothe top surface of the guide plate.

At block 1804, and with reference to FIG. 26A, spray WD-40 into largehole. Insert ⅜″ drill bit into large guide hole (large left hole asshown). Do not start drill until bit is fully inserted in the guidehole. Apply moderate pressure and drill until the bit penetrates theright side wall. Do not drill through both sides.

At block 1806, and with reference to FIGS. 26B-C, spray WD-40 into bothsmall holes. Insert 19/64″ drill bit into either remaining guide holes.Do not start drill until bit is fully inserted in the guide hole. Applymoderate pressure and drill until the bit penetrates the right sidewall. Do not drill through both sides. Repeat in last remaining hole.

At block 1808, unclamp jig assembly from vise and flip it over so theleft side plate is facing up and re-clamp by the guide plate 1. Ensurethat assembly is level. Use a rag or cardboard between the vise andguide plate to prevent damage to the top surface of the guide plate.

At block 1810, and with reference to FIGS. 26D-E, spray WD-40 into bothsmall holes. Insert 19/64″ drill bit into either small guide hole. Donot start drill until bit is fully inserted in the guide hole. Applymoderate pressure and drill until the bit penetrates the left side wall.Continue drilling so the bit passes through the opposite side wallconnecting the holes from either side. Repeat on remaining small hole.

At block 1812, and with reference to FIGS. 26F-G, spray WD-40 into largehole. Insert ⅜″ drill bit into large guide hole. Do not start drilluntil bit is fully inserted in the guide hole. Apply moderate pressureand drill until the bit penetrates the right side wall. Continuedrilling so the bit passes through the opposite side wall connecting theholes from either side.

FIG. 19 depicts a method 1900 of lower receiver removal using a jigassembly according to one or more aspects of the disclosure.

One advantage of the presently described jig assembly or assemblies isthey do not require the user to completely disassemble the jig assemblyto remove or mount an 80% lower receiver.

At block 1902, and with reference to FIG. 27A, remove two #8-32 screws15 from the buffer adapter 7.

At block 1904, and with reference to FIG. 27B, remove short quickrelease pin 11 from front takedown adapter.

At block 1906, and with reference to FIG. 27C, remove ¼-20×2″ screw fromleft side plate 4 using 3/16″ Allen wrench.

At block 1908, and with reference to FIG. 27D, the jig assembly andlower receiver should now be separable. For the AR-308 router jig,loosening or removing one of the side plates 3, 4 may be employed toextract the lower receiver.

At block 1910, and with reference to FIG. 27E, unthread the bufferadapter 7 from the lower receiver.

FIG. 20 depicts various components of a jig assembly with reference toFIGS. 13-19 and 21-27, as described below:

1. Guide Plate (e.g. guide plate 108 described above); 2. Drill Guide;3. Right Side Plate (e.g., carriage 114 as described above); 4. LeftSide Plate (e.g., carriage 302 as described above); 5. Router Adapter(e.g., power tool adapter 122); 6. Router Adapter Side Block; 7. BufferAdapter (e.g., rear support 110 as described above); 8. Front TakedownAdapter (e.g., front support 118); 9. Guide Pin Set (e.g., 908 asdescribed above); 10. Long Quick Release Pin (e.g., corresponding tolocating pin 306); 11. Short Quick Release Pin (e.g., corresponding topin 704); 12. (5) M4×10 Phillips Truss Screw (e.g., adapter screw 906 asdescribed above); 13. (1) ¼″-20×2″ Socket Screw (e.g., carriage screw304 as described above); 14. (6) ¼″-20×⅝″ Socket Screws (e.g., platescrews 106 as described above); 15. (8) #8-32×⅝″ Phillips Screws (e.g.,plate screws 120 as described above).

It should be clear that the above-described jig for manufacturing afirearm lower receiver is a universal fitment and facilitates in theguidance of the rotary tool without placing the rotary tool in directcontact with any of a plurality of guidance features for firearm lowerreceiver manufacturing. It is straightforward to use, resists wear andproduces accurate and repeatable results in the hands of both skilledand unskilled users.

The foregoing has been a detailed description of illustrativeembodiments of the invention. Various modifications and additions can bemade without departing from the spirit and scope if this invention. Eachof the various embodiments described above may be combined with otherdescribed embodiments in order to provide multiple features. As usedherein the directional terms, such as, but not limited to, “up” and“down”, “upward” and “downward”, “rear”, “rearward” and “forward”, “top”and “bottom”, “inside” and “outer”, “front” and “back”, “inner” and“outer”, “interior” and “exterior”, “downward” and “upward”,“horizontal” and “vertical” should be taken as relative conventionsonly, rather than absolute indications of orientation or direction withrespect to a direction of the force of gravity. Furthermore, while theforegoing describes a number of separate embodiments of the apparatusand method of the present invention, what has been described herein ismerely illustrative of the application of the principles of the presentinvention. For example, the foregoing jig can be adapted to machiningand finishing other parts for a firearm, such as portions of an upperreceiver that is being repaired, modified or fabricated. Moreover, thejig can be sold as part of a kit with additional right and leftcarriages and guide pins that are adapted for machining other firearms(for example, polishing the internal surfaces or repairing a restoredfirearm). This jig can be adapted for firearms of various sizes andshapes by interchanging the carriages, thereby providing a jig that canbe useful to a person finishing a firearm, and repairing and/orrestoring a firearm. Also, it is expressly contemplated that the sizeand shape of the plates of the jig can vary. In general, they are sizedin an embodiment proportionally to the depiction herein relative to thesize of the lower receiver. Accordingly, this description is meant to betaken only by way of example, and not to otherwise limit the scope ofthis invention.

What is claimed is:
 1. (canceled) 2-20. (canceled)
 21. A jig formanufacturing a lower receiver comprising: an adapter configured tosupport a rotary power tool above the lower receiver; a guide platedisposed relative to the adapter such that the guide plate is configuredto be disposed below a top surface of the lower receiver; and at leastone support feature configured to engage with the guide plate.
 22. Thejig of claim 21, wherein the at least one support features comprises atleast one of: a rear support configured to engage with the guide plate;a front support configured to engage with the guide plate; or at leastone carriage.
 23. The jig of claim 22, wherein the at least one carriagecomprises: a left carriage; or a right carriage.
 24. The jig of claim23, further comprising at least one locating pin.
 25. The jig of claim21, wherein the jig is constructed and rearranged to be a universalfitment onto the rotary power tool for use in firearm lower receivermanufacturing.
 26. The jig of claim 21, further comprising: a bearing tosupport the rotary tool for use in firearm lower receiver manufacturing.27. The jig of claim 21, wherein the jig is constructed and arranged toprovide for use of at least one guiding feature to facilitate in theguidance of the rotary tool without placing the rotary tool in directcontact with any of a plurality of guidance features for firearm lowerreceiver manufacturing.
 28. The jig of claim 21, wherein a removablelocating pin is situated in a location along front and rear takedown pinholes, that are not threaded, of a firearm receiver and is provided withat least one of a pull, a string or other handle for forearm lowerreceiver manufacturing.
 29. The jig of claim 22, wherein the at leastone carriage includes guide holes that receive a drill bit to form holesin a side of a lower receiver.
 30. The jig of claim 21, furthercomprising: a power tool mount configured to engage with the adapter andconfigured to receive the rotary power tool.
 31. The jig of claim 21,wherein the rear support is threaded into a rear buffer mount of thelower receiver.
 32. The jig of claim 31, wherein the rear supportdefines a plurality of rear support threaded holes that align with aplurality of guide plate threaded holes, the plurality of rear supportthreaded holes arranged within a circumference of the rear buffer mountof the lower receiver.
 33. The jig of claim 21, wherein the guide platehas a thickness between ⅛ inch and ½ inch.
 34. The jig of claim 21,wherein the adapter defines a through-hole for a rotary tool to passtherethrough.
 35. The jig of claim 21, wherein the adapter defines aplurality of wells at an undersurface thereof, the wells beingconfigured to align the adapter with respect to the rotary power tool.36. The jig of claim 21, wherein the adapter is configured to receive aguide pin, the guide pin being configured to engage with the adapter andalign the adapter with respect to the guide plate.
 37. The jig of claim21, wherein the guide plate engages with the adapter.